Catalyzed reaction of an arylamine with an alkylamine to form an n-alkyl substituted arylamine

ABSTRACT

A PRIMARY OR SECONDARY ARYL OR ALKARYLAMINE IS REACTED WITH AN ALKYLAMINE UNDER LIQUID PHASE CONDTIONS IN THE PRESENCE OF A RUTHENIUM, OSMIUM, RHENIUM, OR TECHNETIUM-CONTAINING CATALYST, PREFERABLY IN COMPLEX ASSOCIATION WITH A BIPHYLLIC LIGAND, TO PRODUCE AN ARYL OR ALKARYL AMINE HAVING A NITROGEN-BONDED ALKYL GROUP. A TYPICAL PROCESS COMPRISES CONTACTING ANILINE WITH TRIBUTYLAMINE IN A LIQUID REACTION MEDIUM CONTAINING A MINOR AMOUNT OF RUTHENIUM TRICHLORIDE AND TRIPHENYLPHOSPHINE TO PRODUCE N-BUTYL ANILINE AND DIBUTYLAMINE.

United States Patent 3,737,459 CATALYZED REACTION OF AN ARYLAMINE WITH AN ALKYLAMINE TO FORM AN N- ALKYL SUBSTITUTED ARYLAMINE Donald M. Fenton, Anaheim, Calif., assignor to Union Oil Company of California, Los Augeles, Calif. No Drawing. Filed Aug. 12, 1970, Ser. No. 63,308 Int. Cl. C07c 87/62 US. Cl. 260-577 14 Claims ABSTRACT OF THE DISCLOSURE A primary or secondary aryl or alkyarylamine is reacted with an alkylamine under liquid phase conditions in the presence of a ruthenium, osmium, rhenium, or technetium-containing catalyst, preferably in complex association with a biphyllic ligand, to produce an aryl or alkaryl amine having a nitrogen-bonded alkyl group. A typical process comprises contacting aniline with tributylamine in a liquid reaction medium containing a minor amount of ruthenium trichloride and triphenylphosphine to produce N-butyl aniline and dibutylamine.

DESCRIPTION OF THE INVENTION The invention relates to the preparation of secondary and tertiary arylamines containing one or more nitrogenbonded alkyl groups. More particularly, the invention relates to a method of producing such amines from a primary or secondary arylamine and an alkylamine.

The preparation of secondary and tertiary aryl or alkaryl amines containing a nitrogen-bonded alkyl radical is known in the art. For example, N-ethylaniline is prepared by heating aniline and ethyl alcohol in the presence of sulphuric acid. While preparation of the products of this invention is known, a method wherein a primary or secondary arylamine is reacted with a primary or alkylamine to form an aryl or alkyaryl amine having one or more additional alkyl groups bonded to a nitrogen is not believed to be known in the art.

According to the invention, a primary or secondary arylamine or alkaryl amine is contacted with an alkylamine in the presence of a ruthenium, osmium, rhenium or technetium-containing catalyst, preferably, but not necessarily, in complex association with a biphyllic ligand, e.g., triphenylphosphine, at a temperature of 50400 C. and a pressure of l-200 atmospheres, sufficient to maintain liquid phase reaction conditions.

An exemplary process wherein aniline is reacted with tributylamine is as follows:

It can be seen from the foregoing equation that an alkyl group of the alkylamine replaces a hydrogen of the arylamine. In the case where the arylamine is a primary amine and the alkylamine is a dialkyl or trialkyl amine, one or more alkyl groups can be transferred from the alkylamine to the arylamine. Thus, primary or secondary arylamines can be converted to secondary or tertiary arylamines containing one or two alkyl radicals, respectively, bonded to the nitrogen.

The arylamine of the invention is a primary or secondary mono-nuclear aryl or alkaryl amine having 6 to 25 carbons, preferably 6 to 15 carbons, and having the following general structure:

wherein R is mono-nuclear aryl or alkaryl having 6 to 18, preferably 6 to 12 carbons, and R is hydrogen or alkyl 3,737,459 Patented June 5, 1973 having 1 to 12, preferably 1 to 8 carbons, and is preferably hydrogen. The alkyl group(s) associated with R preferably have 1 to 8, most preferably, 1 to 4 carbons.

Examples of suitable primary and secondary arylamines or alkarylamines are aniline, p-ethylaniline, p-octylaniline, 2-butyl-3-ethylaniline, 2-methyl-4-nonylani1ine, 2,3,5-triethylaniline, N-methylaniline, N-propylaniline, N-octylaniline, N-dodecylaniline, N-butyl-p-ethylaniline, N-2- butyloctylaniline, N-nonyl-Z,3-dipentylaniline, N-Z-octylhexyl-3-propylaniline, etc., examples of the preferred primary aryl or alkaryl amines being aniline, 2,4-dimethylaniline, p-propylaniline, 2,3,4-tributylaniline, etc.

The alkylamine reactant -of the invention may be a primary, secondary or tertiary alklamine, preferably a secondary or tertiary alkylamine, most preferably a tertiary amine having the structure:

wherein R is hydrogen or the same or different alkyl group having 1 to 18 carbons, preferably 1 to 12 carbons, e.g., methyl; ethyl; propyl; 'butyl; hexyl; nonyl; dodecyl; 2-propyldecyl; tetradecyl; hexadecyl; octadecyl; S-butylnonyl; 2,4-dipentyloctyl; etc.

Examples of suitable alkylamines are methylamine, propylarnine, butylamine, isobutylamine, pentylamine, hexylamine, heptylamine, 2-propylheptylamine, 2-butyl-3- pentyloctylamine, octylamine, nonylamine, dodecylamine, octadecylamine, diethylamine, dibutylamine, dioctylamine, diundecylamine, butylethylamine, propyloctylamine, butyldodecylamine, isobutyl-2-hexylnonylamine, tributylamine, trioctylamine, tri3-butyldecylamine, methyldibutylamine, hexylnonyldecylamine, 2-pentyldecyldimethylamine, etc. Examples of the most preferred tertiary alkylamines with hydrocarbon groups having 1 to 8 carbons are trimethylamine, tripropylamine, tributylamine, triisobutylamines, tripentylamine, tri-3-methylpentylamine, trihexylamine, diethylhexylamine, triheptylamine, trioctylamine, dimethylpentylamine, etc.

The catalyst of the invention may comprise ruthenium, osmium, rhenium or technetium, preferably ruthenium. A minor amount of the catalyst is used, e.g., 0.001-5 weight percent, preferably 0.00l-2 percent calculated as the metal and based on the reaction medium. The metal may be added as a salt, e.g., halide (chloride, bromide, iodide or fluoride), nitrate, nitrite, sulfate, sulfite, bisulfite, cyanide, carbonate, bicarbonate, C -C carboxylate, etc., or as a complex. Typical complexes are disclosed in Advanced Inorganic Chemistry, Second edition, by Cotton and Wilkinson, pages 960 to 1009; typical ligands of such complexes disclosed as being halo (chloro, fluoro, bromo and iodido), hydrido, cyano, nitrido, amino, carbonyl, oxo, hydroxo, triphenylphosphino, etc. The metal may also be added as a free metal. When the free metal is added, it is preferred to include a complexing ligand or anion in the reaction system such that the free metal forms a complex in situ. Preferbaly, the catalyst is added as a halide; preferably chloride.

Suitable sources of the metal catalyst include ruthenium tetrachloride, ruthenium trichloride, ruthenium cyanide, ruthenium pentacarbonyl, ruthenium carbonyl hydride, tris(triphenylphosphine)ruthenium chloride, potassium hexafiuororuthenate, ruthenium hydroxochloride, ruthenium nitrate, ruthenium hydroxide, ruthenium sulfide, tetraaminorutheniumhydroxychloro chloride, ruthenium acetate, ruthenium benzoate, osmium dichloride, sodium osmiamate, sodium hydroxopentachloroosmate, lithium hexafluoroosmate, rhodium pentanitritoosmate, osmium iodide, osmium oxide, osmium nitrate, oxoosmium chloride, osmium sulfite, chloroosmic acid, osmium valerate, osmium sulfate, tetraaminoosmiumhydroxy chloride, ruthenium bromide, rhenium pentacarbonyl, potassium perrhenate, ruthenium chloride, rhenium dioxide, rhenium heptoxide, rhenium sulfide, potassium hexacyanorhenate, lithium hexachlorotechnetate, trimethylrhenium, dipyridyl perrhenate, technetium chloride, ditechnetium decacarbonyl, sodium nonahydridorhenate, sodium pertechnetate, technetium nitrate, technetium oxide, etc. The particular method by which the metal is added to the reacion medium is not the essence of the invention nor particularly critical to the reaction.

The process is preferably conducted in the presence of a biphyllic ligand which forms a complex with and stabilizes the aforementioned catalyst. Use of a biphyllic ligand is, however, not essential to the process. The biphyllic ligand is a compound having at least one atom with a pair of electrons capable of forming a coordinate covalent bond with a metal atom and simultaneously having the ability to accept the electron from the metal, thereby imparting additional stability to the resulting complex. Biphyllic ligands are well known in the art and can comprise organic compounds having at least about 3 carbons and containing arsenic, antimony, phosphorus or bismuth in a trivalent state. Of these the phosphorus compounds, i.e., the phosphines, are preferred; however, the arsines, stibines and bismuthines can also be employed. In general, these biphyllic ligands have the following structure:

wherein E is trivalent phosphorus, arsenic, antimony or bismuth;

and wherein R is the same or different alkyl having 1 to about carbons, cycloalkyl having 4 to about 10 carbons and/or aryl having 6 to about 10 carbons, examples of which are methyl, butyl, nonyl, cyclohexyl, cyclodecyl, phenyl, tolyl, xylyl, duryl, etc. Preferably at least one R is aryl, e.g., phenyl, tolyl, xylyl, etc., and most preferably, the ligand is triaryl.

Examples of suitable biphyllic ligands having the aforementioned structure and useful in my invention to stabilize the catalyst composition are the following: trimethylphosphine, triethylarsine, triethylbismuthine, triisoproplstibine, dioctylcycloheptylphosphine, tricyclohexylphosphine, ethyldiisopropylstibine, tricyclohexylphosphine, methyldiphenylphosphine, methyldiphenylstibine, triphenylphosphine, triphenyibismuthine, tri(o-tolyl)phosphine, ethyldiphenylphosphine, phenylditolylphosphine, phenyldiisopropylphosphine, phenyldiamylphosphine, xylyldiphenylarsine, tolyldi(m-xylyl)stibine, tfixylylphosphine, trixylylarsine, trixylylstibine, cyclopentyldixylylstibine, dioctylphenylphosphine, tridurylphosphine, tricumenylphosphine, trixylylbismuthine, etc. Of the aforementioned, the mono-, diand triaryl phosphines, particularly the triarylphosphines (e.g., triphenylphosphine), are preferred because of their greater activity.

The catalyst may be complexed with the above-described biphyllic ligand before being introduced into the reaction medium or the complex may be formed in situ by simply adding the metal and the biphyllic ligand directly into the reaction medium. In either case, it is generally preferable that the quantity of biphyllic ligand be in excess, e.g., 10 percent to 300 percent of that stoichiometrically required to form a complex with the metal and is generally 0.01-10 weight percent of the reaction medium. The complex has from 1 to about 5 moles of biphyllic ligand per atom of the metal and other components such as hydride, or soluble anions such as sulfate, nitrate, C -C carboxylates (e.g., acetate, propionate, isobutyrate, valerate, etc.), halide, etc., may be but need not be included in the complex catalyst of this in- 'vention. These components may be incorporated in the catalyst by the formation of the catalyst complex from a metal salt of the indicated anions. A preferred complex is one comprising at least one halide ligand, e.g., acetate, propionate, butyrate, benzoate, etc., since these groups, particularly the halides, improve the activity of the caty t.

The process is preferably conducted in the presence of 0. 01-1'0 weight percent, preferably 0.01-5 percent of a strong base such as the alkali or alkaline earth metal hydroxides, e.g., sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, magnesium hydroxide, etc. Since the nitrogen containing reactant and the product are alkaline, the addition of further alkaline agents is not essential to operability but is only preferred for maximum activity.

The reaction is performed under liquid phase conditions. When the reactants and/or product are liquids under the reaction conditions, they can form the desired liquid phase and be diluted, if desired, with a suitable inert organic liquid, preferably a liquid which is a solvent for the reactants and catalyst. Suitable liquids include the saturated and aromatic hydrocarbons which are exemplified by hexane, heptane, octane, benzene, toluene, cyclohexane, cyclodecane, etc.

The liquid phase can also be formed simply by use of an excess of one or both of the reactant amines if liquids, e.g., 210() times that stoichiometrically required for the reaction. This can be accomplished by use of an excess of one of the two reactants.

The process may be conducted at mild conditions such as temperatures of 50400 C., preferably 150-350 C., most preferably 200-300 C. and pressures of 1-200 atmospheres absolute, preferably 1-70 atmospheres and To a 250 milliliter flask were added 60 milliliters trisuflicient to maintain liquid phase conditions. The desired pressure may be maintained by adding an inert gas, e.g., nitrogen, to the reaction mixture, however, addition of an inert gas is generally not required.

The reaction can be performed batchwise or in a continuous fashion. When operating batchwise, the catalyst, reaction medium, the reactant amines, and the strong base, if utilized, can be introduced in the reaction zone to form a liquid phase therein. The reaction zone can be heated to the desired reaction temperature by preheating the liquid so introduced or by use of heating means in the reactor. In the case where an inert gas is utilized, the inert gas can be introduced to maintain the desired reaction pressure. When performing the reaction in a continuous fashion, the liquid components can be continuously charged to the reaction zone to maintain a liquid phase therein and amine reactants can be continuously introduced into the reaction zone to contact the reaction medium containing the catalyst. To enhance the mixing of the reactants, the gaseous reactants can be bubbled directly into the liquid phase and/or the liquid phase can be thoroughly agitated by suitable mixers.

The product arylamine can be recovered from the reaction zone by periodically or continuously withdrawing at least a portion of the liquid reaction medium and the amine may be recovered therefrom by conventional separation processing such as distillation. The remainder of the reaction medium may be recycled to the reaction zone.

The progress is preferably conducted in the presence of a biphyllic ligand which forms a complex with and stabilizes the aforementioned catalyst. Use of a biphyllic ligand is, however, not essential to the process.

EXAMPLE 1 The following examples illustrate the invention and demonstrate the results actually obtained. butylamine, 60 milliliters aniline, V2 gram ruthenium trichloride and 3 grams triphenylphosphine. The mixture was heated to reflux for about 24 hours. The liquid contents were removed to reveal that 6 grams of N-butylaniline and 3 grams of dibutylamine were formed in the process.

To a 250 milliliter flask were added 50 milliliters of di- 1 butylamine, 50 milliliters of aniline, 3 grams triphenylture was heated to reflux for 24 hours. The liquid contents were removed to reveal that 14 grams of N-butylaniline, and 7 grams N,N-dibutylaniline were formed in the process.

EXAMPLE 2 The following examples illustrate other modes of practice presently contemplated.

To an autoclave are added 400 milliliters of 2,4-dioctylaniline, 300 milliliters propylamine, 5 grams osmium nitrate and 15 grams tritolylarsine. The autoclave is pressured with nitrogen to atmospheres and heated to and maintained at 250 C. for 10 hours. The liquid contents are removed and N-propyl-Z, 4 dioctylaniline is recovered 'by distillation.

To an autoclave are added 400 milliliters N-hexylaniline, 200 milliliters of dodecylamine, 10 grams of osmium nitrate and 50 milliliters of tributylbismuthine. The autoclave is pressured with nitrogen to atmospheres and heated to and maintained at 280 C. for 30 hours. The liquid contents are removed and N,N-dodecylhexylaniline is separated by distillation.

To an autoclave are added 200 milliliters aniline, 250 milliliters propylamine and 5 grams rutheium trichloride. The autoclave is pressured with nitrogen to 5 atmospheres and heated to and maintained at 150 C. for 6 hours. The liquid contents are removed and N- propylaniline is recovered by distillation.

To an autoclave are added 200 milliliters N-butyl-2,3- dipropylaniline, 200 milliliters ethyldidodecylamine, 10 grams osmium chloride and grams tritolylphosphine. The autoclave is pressured with nitrogen to 20 atmospheres and heated to and maintained at 250 C. for 50 hours. The liquid contents are removed and N,N-butylethyl 2,3 dipropylaniline and N,N-butyldodecylaniline are recovered by distillation.

To an autoclave are added 300 milliliters N-octyl-3- methyl 4 nonylaniline, 300 milliliters triheptylamine, 10 grams ruthenium sulfate and 20 grams tributylstibine. The autoclave is pressured with nitrogen to 20 atmospheres and heated to and maintained at 350 C. for 10 hours. The liquid contents are recovered and N,N-octylheptyl 3 methyl 4 nonylaniline is recovered by distillation.

It is apparent that other amines, catalysts and biphyllic ligands described herein may be substituted for those of the preceding examples without departing from the illustrated mode of practice. The foregoing examples are not to be construed as limiting the invention which is to be defined only by the following claims.

I claim:

-1. A process for the preparation of an N-substituted aryl or alkaryl amine by reacting an aryl or alkaryl amine having 6 to carbons and having the formula:

wherein R is phenyl or phenyl substituted by alkyl of 1 to 12 carbons and R is hydrogen or alkyl having 1 to 12 carbons with a primary, secondary or tertiary alkylamine reactant having the formula:

wherein at least one of said R" groups is an alkyl group having 1 to 18 carbons and the other R" groups are hydrogen or the same or diiferent alkyl groups having 1 to 18 carbons in a liquid reaction medium containing 0.001-5 weight percent of a ruthenium, or osmium, complex thereof with a biphyllic ligand having the structure:

wherein E is trivalent phosphorus, arsenic, antimony or bismuth, and wherein R"" is the same or different alkyl having 1 to about 10 carbons, cycloalkyl having 4 to about 10 carbons or aryl having 6 to about 10 carbons; at a temperature of 50-400 C. and a pressure of 1-200 atmospheres, suflicient to maintain liquid phase reaction conditions and to transfer one of said R groups of said (R") N reactant to the nitrogen of said aryl or alkaryl amine and thereby increase the substitution of the nitrogen of said amine.

2. The process of claim 1 wherein R of the aryl or alkaryl amine is hydrogen.

3. The process of claim 1 wherein the aryl or alkaryl amine is aniline.

4. The process of claim 1 wherein said reaction medium contains from 0.01 to 10.0 weight percent of an alkali or alkaline earth metal hydroxide.

5. The process of claim 1 wherein said reaction medium contains from 0.01 to 5.0 weight percent of an alkali or alkaline earth metal hydroxide.

6. The process of claim 1 wherein the reaction medium contains a biphyllic ligand complex of ruthenium.

7. The process of claim 6 wherein the reaction medium contains a triarylphosphine complex of ruthenium.

8. The process of claim 7 wherein the aryl or alkaryl amine is aniline.

9. The process of claim 7 wherein the complex is a triphenylphosphine complex of ruthenium.

10. The process of claim 7 wherein said alkylamine is a tertiary amine and R of the aryl or alkaryl amine is hydrogen.

11. The method of claim 10 wherein the process is conducted at a temperature of 200300 C.

12. The process of claim 10 wherein the complex is formed by the addition of ruthenium halide and the biphyllic ligand to the reaction medium.

13. The process of claim 10 wherein said R of said alkylamine has 1 to 8 carbons, wherein said aryl or alkaryl amine is aniline, wherein said tn'arylphosphine is triphenylphosphine, wherein the process is conducted at a temperature of 200-300 C. and wherein the complex is formed by the addition of ruthenium halide and the biphyllic ligand to the reaction medium.

14. The method of claim 13 wherein said alkylamine is tributylamine.

References Cited Houben-Weyl, Band XI/ 1, Amine, George Thieme Verlag: Stuttgart. 1957, pp. 248-261.

LEWIS GOTIS, Primary Examiner C. F. WARREN, Assistant Examiner US. Cl. X.R.

260576; 252-428, 429 R, 431 R, 431 C, 431 P 

